<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="js/vue.js"></script>
</head>
<body>
    <div id="app">
        <div :class="cnameArr">这是div</div>
        <button @click="handleAdd">添加数组</button>
    </div>
    <script>
        const vm = new Vue({
            el:"#app",
            data:{
                cnameArr:['aa','bb','cc']
            },
            methods: {
                handleAdd(){
                    this.cnameArr.push('dd')
                }
            },
        })
        //动态添加class属性
        // Vue.set(vm.cnameObj,"dd",true)
    </script>
</body>
</html>